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People are being seriously harmed and in some cases killed by overdiagnosis and unnecessary treatment, one of the country's leading specialists warns. Nicholas Jones hears why health workers are being urged to think twice before ordering a test or procedure.

Medicine's ability to help the sick could soon be outstripped by a propensity to harm the healthy.

That's the firm view of Dr John Bonning, the first Kiwi to be elected to head the Australasian College for Emergency Medicine in its 35-year history.

Bonning is also involved with the New Zealand chapter of the international Choosing Wisely movement, started by health workers worried that over-treatment is seriously harming patients, even killing them.

"We really are harming patients," he said. "Healthcare is getting more and more complex - our ability to do stuff is growing, we have more treatments. But in trying to be good doctors, sometimes you can inadvertently cause harm."

The problem cuts across many areas of health, Bonning said - from overuse of antibiotics to unnecessary scans showing tissue growth (that turns out to be benign), which are checked with biopsies that lead to dangerous infections.

"Somebody has been in a nasty car crash. You are fairly certain they don't have major injury but they're a little bit bruised. And there are a lot of people who think, 'If I don't scan this person and they have so much as a broken rib, I will be held to account by the Health and Disability Commissioner, or I'll be sued.'

"So it's just so easy - order the CT scan. It abdicates all responsibility - 'I won't miss that tiny injury.' Whereas, there's actually an 86 per cent chance of finding an incidental abnormality that's not harmful and will not cause disease or problems but will cause concern, worry and a desire for people to have things looked into further."

Health workers have started a movement to discourage overdiagnosis and treatment. Photo / 123rf

In the most extreme cases, overtreatment can kill. Bonning gives an example of a 22-year-old in the United States who was on medication, Valproate, for epilepsy.

In a very small number of people that medication can cause liver damage, which leads to jaundice - a condition that causes a person to look and feel unwell. The patient moved towns and went to a new doctor for a repeat prescription. Despite no signs of sickness, a blood test was done which showed liver function slightly out of normal range. An ultrasound showed a cyst and a biopsy was taken.

"A week later, he got really sick and had an infection where they put the needle into the liver. [The patient] developed a really nasty bug and died. The biopsy subsequently showed the cyst was completely benign," Bonning said.

"It was a cyst he was hopefully going to take to his grave in his 70s or 80s but he died at 22. Because somebody had done a blood test. That's extreme. However, this is the potential for this.

"And if you do a CT scan of somebody's head, you might find a little extra nubbin of tissue around the pituitary gland. Or in the abdomen you might find it on the adrenal. These are called incidentalomas - incidental findings of slight abnormalities."

Bonning said other areas prone to overdiagnosis included screening low-risk populations for prostate cancer, prescribing unnecessary medications, and checks for pulmonary embolism - a clot in the lung, which can start after deep vein thrombosis in the legs.

"In America, their medical-legal system stipulates a zero miss culture and you risk being sued. So everybody has to chase down every single person that comes in saying, 'Oh, I've got a little niggle on my rib,'" he said of tests for blood clots.

"And instead of saying, 'It's probably bruised, or a little muscle strain, or the cartilage is inflamed,' you get scans. Their pattern of CT screening for pulmonary embolisms is harming and in fact killing six times more patients than it is helping; six times more people are harmed or killed as a result of these scans. It's not just the scans causing cancer [by radiation exposure], it's the scans causing incidental findings that are then investigated."

Blood tests can lead to a "cascade" of ultimately unnecessary treatment. Photo / Mike Scott

Ordering extra tests or treatment also uses up precious health resources, Bonning said. A CT scanner can do only so many scans a day and an overly cautious approach means potentially harmful delays for people in real need.

"Our emergency departments are absolutely chocka. Every single day. Masses of people come in and we have only a certain amount of resource we can give them. So we want to find the people who are really sick."

The Choosing Wisely campaign encourages health workers and patients to ask four key questions: do I really need to have this test or procedure; what are the risks; are there simpler, safer options; and what happens if I do nothing?

It has published a wide range of specific recommendations , such as that urinalysis or culture shouldn't be performed without clinical evidence of urinary tract infection (agreed with the NZ Microbiology Network), and that antibiotics shouldn't be prescribed for exacerbation of asthma (agreed with the Thoracic Society of Australia and New Zealand).

A recent paper in the NZ Medical Journal warned such guidelines could worsen under-treatment of Māori and other groups. Co-author Professor David Tipene-Leach said recommendations for the entire population could be inappropriate, such as not giving antibiotics for acute upper respiratory tract infections.

"[That] may sound reasonable, given the majority of these infections are viral and antimicrobial resistance is a rising concern. However, for Māori and Pacific children in New Zealand - who experience high rates or rheumatic fever - sore throats should be swabbed and treated with antibiotics until swab results are available."

In response, Choosing Wisely clinical lead Dr Derek Sherwood acknowledged care must be taken to ensure the message "more is not necessarily better" doesn't inadvertently widen health gaps. The campaign has partnered with the Māori Medical Practicioners Association on research.

Choosing Wisely has run for about five years and is an international movement, with chapters in Australia, Canada and the United States. Bonning's own awakening to the issue in part came after reading the best-seller, Overdiagnosed: Making People Sick in the Pursuit of Health, by Professor H. Gilbert Welch, who believes there's an "epidemic" of over-testing and treatment.

Bonning said he understood the enormous pressure on health workers to not miss anything. However, he quoted recent research in The BMJ (formerly called the British Medical Journal) on the significance of overdiagnosis: "Medicine's much vaunted ability to help the sick and injured is soon to be outstripped by our propensity to harm the healthy".

Movements like Choosing Wisely could help avoid such a tipping point, Bonning said, but wider buy-in from the public was needed, particularly as technology allows more finely-tuned tests and potential treatments proliferate.

"I don't want to come across as a medical nihilist; somebody that wants to go back to a course of leeches [but] we really are harming patients. Not recklessly. It is inadvertent, in good faith - trying to do the right thing but ending up doing the wrong thing.

"There are benefits of treatments, but it's not guaranteed. There are harms. There might be alternatives, and there's also the"\: 'What if I do nothing?'"